> A country without a universal franchise has already established that some people don't get a democratic say, it's just haggling over who those people are. And that means it can haggle over whether you get to be one of those people. And even eventually over whether anyone gets to be one of those people, over whether it is democratic at all.

I don't think that inductive reasoning works. Every country excludes lots of people from the franchise. The U.S. has almost 100 million people who aren't eligible to vote, mostly young people and non-citizens. No country has a truly universal franchise. Under your reasoning, that's unstable--if we can take away the franchise from 17 year olds, we can take away the franchise from 18 year olds, etc.

Historically, the big democratic jumps were probably extending the franchise to prominent family heads voting, followed by landowning males.